Sign holder



FIG. 1 is a perspective view of the sign holder design;

FIG. 2 is a front view of the sign holder design;

FIG. 3 is a right side view of the sign holder design, the left side view being a mirror image;

FIG. 4 is a rear view of the sign holder design;

FIG. 5 is a top view of the sign holder design; and,

FIG. 6 is a bottom view of the sign holder design.

The broken lines are shown for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a sign holder, as shown and described. 